Dry etching of TiN in N2/Cl2/Ar adaptively coupled plasma

We investigated the N-2 additive effect on the etch rates of TiN and SiO2 and etch profile of TiN in N-2/Cl-2/Ar adaptively coupled plasma (ACP). The mixing ratio of Cl-2 and Ar was fixed at 75 and 25 sccm, respectively. The N-2 flow rate was increased from 0 to 9 sccm under the constant pressure of 10 mTorr. As N-2 flow rate was increased in N-2/Cl-2/Ar plasma, the etch rate of TiN was linearly increased, but that of SiO2 was increased non-monotonically. The etch profile and the compositional changes of TiN was investigated with field emission-scanning electron microscope (FE-SEM), FE-Auger electron spectroscopy (FE-AES) and x-ray photoelectron spectroscopy (XPS). When 9 sccm N-2 was added into Cl-2/Ar, a steep etch profile and clean surface of TiN was obtained. In addition, the signals of TiN and Ti were disappeared in FE-AES and XPS when N-2 additive flow into Cl-2/Ar was above 6 sccm. From the experimental data, the increase in TiN etch rate was mainly caused by the increase of desorption and evacuation rate of etch by products because of the increased effective pumping speed. The etch mechanism of TIN in N-2/Cl-2/Ar ACP plasma can be concluded as the ion enhanced chemical etch. (C) 2011 Elsevier Ltd. All rights reserved.